1
在这个片段中，我添加了ZXingscanner视图，并且代码完全没有显示任何错误，但是当我运行应用程序时，它崩溃并且每次都停止。此应用程序有3个选项卡，并且其中一个选项卡的片段是此扫描器，但由于某种原因，此视图会将应用程序废弃。这是我的片段类的代码：Android工作室中的LogCat错误，在运行时崩溃的应用程序
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.os.Vibrator;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.Result;
import com.hist_area.imeda.histarea.R;
import java.util.ArrayList;
import java.util.List;
import me.dm7.barcodescanner.zxing.ZXingScannerView;
public class EmptyFragment extends Fragment implements ZXingScannerView.ResultHandler {
public static EmptyFragment create() {
return new EmptyFragment();
}
Vibrator vibrator;
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
private ZXingScannerView mScannerView;
private LinearLayout qrCameraLayout;
@Override
public View onCreateView (LayoutInflater inflater, ViewGroup container, Bundle
savedInstanceState)
{
View v = inflater.inflate(R.layout.fragment_camera, container, false);
qrCameraLayout = (LinearLayout) v.findViewById(R.id.camera_preview);
mScannerView = new ZXingScannerView(getActivity().getApplicationContext());
mScannerView.setLayoutParams(new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.MATCH_PARENT));
qrCameraLayout.addView(mScannerView);
List<BarcodeFormat> formats = new ArrayList<>();
formats.add(BarcodeFormat.QR_CODE);
mScannerView.setFormats(formats);
return v;
}
@Override
public void onResume()
{
super.onResume();
mScannerView.setResultHandler(this); // Register ourselves as a handler for scan results.
mScannerView.startCamera(); // Start camera on resume
}
@Override
public void onPause()
{
super.onPause();
mScannerView.stopCamera();
}
@Override
public void handleResult (final Result result)
{
vibrator.vibrate(369);
Log.e("handleresult", result.getText());
//Hold result
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle(" Scan Result");
builder.setPositiveButton("Scan Again", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
mScannerView.resumeCameraPreview(EmptyFragment.this);
}
});
builder.setNeutralButton("Main Page", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
mScannerView.stopCamera();
MainPageFragment.create();
}
});
builder.setMessage(result.getText());
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
}
而这里的代码，XML的LinearLayout其中有这样的观点：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<View
android:id="@+id/camera_scanner"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
这里的logcat的错误：
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.addView(android.view.View)' on a null object reference
at com.hist_area.imeda.histarea.fragment.EmptyFragment.onCreateView(EmptyFragment.java:52)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2239)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1332)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1574)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1641)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:794)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2415)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2200)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2153)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:2034)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:651)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1239)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1087)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1613)
at android.view.View.measure(View.java:18788)
at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
at android.view.View.measure(View.java:18788)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:18788)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
at android.view.View.measure(View.java:18788)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:18788)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1465)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:748)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:630)
at android.view.View.measure(View.java:18788)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5951)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2643)
at android.view.View.measure(View.java:18788)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2100)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1216)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1452)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
at android.view.Choreographer.doCallbacks(Choreographer.java:670)
at android.view.Choreographer.doFrame(Choreographer.java:606)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at co
08-04 17:29:54.075 4819-4819/com.hist_area.imeda.histarea I/Process: Sending signal. PID: 4819 SIG: 9